[Current concept of pseudodementia].

The concept of pseudodementia was coined in the late XIXth century to refer to a syndrome mimicking dementia, but without underlying neurological lesions. Depressive disorders represent the main etiological factor and may present under two different forms, either "depressive cognitive disorders", or the more severe feature of "Wernicke's pseudodementia". The main issue remains diagnosing pseudodementia form organic dementia, especially from cortical degenerations of the Alzheimer type. Thus, the recognition of this clinical syndrome represents an alternative to the diagnosis of dementia which may lead to earlier and more effective psychiatric treatment. Recently, diagnostic criteria have been proposed to facilitate this distinction. Such criteria include clinical history, neuropsychological features, biological findings (dexamethasone suppression test and plasma MHPG) and electroencephalographic sleep studies. Finally, from a theoretical point of neurological conception of depression as well as for current hypotheses on the relationship of this last one with dementia.